linux/mm
Emese Revfy 38addce8b6 gcc-plugins: Add latent_entropy plugin
This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot time as
possible, hoping to capitalize on any possible variation in CPU operation
(due to runtime data differences, hardware differences, SMP ordering,
thermal timing variation, cache behavior, etc).

At the very least, this plugin is a much more comprehensive example for
how to manipulate kernel code using the gcc plugin internals.

The need for very-early boot entropy tends to be very architecture or
system design specific, so this plugin is more suited for those sorts
of special cases. The existing kernel RNG already attempts to extract
entropy from reliable runtime variation, but this plugin takes the idea to
a logical extreme by permuting a global variable based on any variation
in code execution (e.g. a different value (and permutation function)
is used to permute the global based on loop count, case statement,
if/then/else branching, etc).

To do this, the plugin starts by inserting a local variable in every
marked function. The plugin then adds logic so that the value of this
variable is modified by randomly chosen operations (add, xor and rol) and
random values (gcc generates separate static values for each location at
compile time and also injects the stack pointer at runtime). The resulting
value depends on the control flow path (e.g., loops and branches taken).

Before the function returns, the plugin mixes this local variable into
the latent_entropy global variable. The value of this global variable
is added to the kernel entropy pool in do_one_initcall() and _do_fork(),
though it does not credit any bytes of entropy to the pool; the contents
of the global are just used to mix the pool.

Additionally, the plugin can pre-initialize arrays with build-time
random contents, so that two different kernel builds running on identical
hardware will not have the same starting values.

Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: expanded commit message and code comments]
Signed-off-by: Kees Cook <keescook@chromium.org>
2016-10-10 14:51:44 -07:00
..
kasan kasan: remove the unnecessary WARN_ONCE from quarantine.c 2016-08-11 16:58:14 -07:00
backing-dev.c block: fix bdi vs gendisk lifetime mismatch 2016-08-04 14:19:16 -06:00
balloon_compaction.c mm: balloon: use general non-lru movable page feature 2016-07-26 16:19:19 -07:00
bootmem.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
cleancache.c cleancache: constify cleancache_ops structure 2016-01-27 09:09:57 -05:00
cma_debug.c
cma.c mm/cma: silence warnings due to max() usage 2016-05-27 14:49:37 -07:00
cma.h
compaction.c mm, compaction: simplify contended compaction handling 2016-07-28 16:07:41 -07:00
debug_page_ref.c mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
debug.c mm: avoid endless recursion in dump_page() 2016-09-19 15:36:16 -07:00
dmapool.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
early_ioremap.c
fadvise.c mm/fadvise.c: do not discard partial pages with POSIX_FADV_DONTNEED 2016-06-09 14:23:11 -07:00
failslab.c mm: fault-inject take over bootstrap kmem_cache check 2016-03-15 16:55:16 -07:00
filemap.c mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page() 2016-09-30 15:26:52 -07:00
frame_vector.c mm/gup: Switch all callers of get_user_pages() to not pass tsk/mm 2016-02-16 10:11:12 +01:00
frontswap.c mm, frontswap: convert frontswap_enabled to static key 2016-07-26 16:19:19 -07:00
gup.c - ARM: GICv3 ITS emulation and various fixes. Removal of the old 2016-08-02 16:11:27 -04:00
highmem.c mm/highmem: make nr_free_highpages() handles all highmem zones by itself 2016-05-19 19:12:14 -07:00
huge_memory.c mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing 2016-09-25 15:43:42 -07:00
hugetlb_cgroup.c mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size 2016-05-20 17:58:30 -07:00
hugetlb.c mm/hugetlb: fix incorrect hugepages count during mem hotplug 2016-08-11 16:58:13 -07:00
hwpoison-inject.c
init-mm.c
internal.h mm, compaction: simplify contended compaction handling 2016-07-28 16:07:41 -07:00
interval_tree.c
Kconfig mm: clarify COMPACTION Kconfig text 2016-08-26 17:39:35 -07:00
Kconfig.debug mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
khugepaged.c mm, thp: fix leaking mapped pte in __collapse_huge_page_swapin() 2016-09-19 15:36:16 -07:00
kmemcheck.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak-test.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak.c kmemleak: don't hang if user disables scanning early 2016-07-28 16:07:41 -07:00
ksm.c mm,ksm: fix endless looping in allocating memory when ksm enable 2016-09-28 16:19:01 -07:00
list_lru.c mm: memcontrol: move kmem accounting code to CONFIG_MEMCG 2016-01-20 17:09:18 -08:00
maccess.c x86: remove more uaccess_32.h complexity 2016-05-22 17:21:27 -07:00
madvise.c mm: make mmap_sem for write waits killable for mm syscalls 2016-05-23 17:04:14 -07:00
Makefile Implements HARDENED_USERCOPY verification of copy_to_user/copy_from_user 2016-08-08 14:48:14 -07:00
memblock.c mm/memblock.c: fix NULL dereference error 2016-08-04 20:02:09 -04:00
memcontrol.c mm: memcontrol: make per-cpu charge cache IRQ-safe for socket accounting 2016-09-19 15:36:17 -07:00
memory_hotplug.c mem-hotplug: use nodes that contain memory as mask in new_node_page() 2016-09-28 16:19:02 -07:00
memory-failure.c mm: hwpoison: remove incorrect comments 2016-07-28 16:07:41 -07:00
memory.c mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing 2016-09-25 15:43:42 -07:00
mempolicy.c mm, mempolicy: task->mempolicy must be NULL before dropping final reference 2016-09-01 17:52:01 -07:00
mempool.c Revert "mm, mempool: only set __GFP_NOMEMALLOC if there are free elements" 2016-07-28 16:07:41 -07:00
memtest.c
migrate.c mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations 2016-07-28 16:07:41 -07:00
mincore.c mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
mlock.c mm, vmscan: move LRU lists to node 2016-07-28 16:07:41 -07:00
mm_init.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
mmap.c mm: refuse wrapped vm_brk requests 2016-08-02 19:35:15 -04:00
mmu_context.c mm/mmu_context, sched/core: Fix mmu_context.h assumption 2016-04-28 11:44:19 +02:00
mmu_notifier.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
mmzone.c mm, page_alloc: inline the fast path of the zonelist iterator 2016-05-19 19:12:14 -07:00
mprotect.c mm: thp: check pmd_trans_unstable() after split_huge_pmd() 2016-07-26 16:19:19 -07:00
mremap.c mm: thp: check pmd_trans_unstable() after split_huge_pmd() 2016-07-26 16:19:19 -07:00
msync.c
nobootmem.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
nommu.c mm: introduce fault_env 2016-07-26 16:19:19 -07:00
oom_kill.c mm, oom: fix uninitialized ret in task_will_free_mem() 2016-08-11 16:58:14 -07:00
page_alloc.c gcc-plugins: Add latent_entropy plugin 2016-10-10 14:51:44 -07:00
page_counter.c
page_ext.c mm: use early_pfn_to_nid in page_ext_init 2016-05-27 14:49:37 -07:00
page_idle.c mm, vmscan: move lru_lock to the node 2016-07-28 16:07:41 -07:00
page_io.c mm: fix the page_swap_info() BUG_ON check 2016-09-19 15:36:17 -07:00
page_isolation.c mm/page_isolation: clean up confused code 2016-07-26 16:19:19 -07:00
page_owner.c mm/page_owner: use stackdepot to store stacktrace 2016-07-26 16:19:19 -07:00
page_poison.c mm: check the return value of lookup_page_ext for all call sites 2016-06-03 15:06:22 -07:00
page-writeback.c mm: remove reclaim and compaction retry approximations 2016-07-28 16:07:41 -07:00
pagewalk.c thp: rename split_huge_page_pmd() to split_huge_pmd() 2016-01-15 17:56:32 -08:00
percpu-km.c mm: percpu: use pr_fmt to prefix output 2016-03-17 15:09:34 -07:00
percpu-vm.c
percpu.c percpu: fix synchronization between synchronous map extension and chunk destruction 2016-05-25 11:48:25 -04:00
pgtable-generic.c mm/thp/migration: switch from flush_tlb_range to flush_pmd_tlb_range 2016-03-17 15:09:34 -07:00
process_vm_access.c mm/gup: Introduce get_user_pages_remote() 2016-02-16 10:04:09 +01:00
quicklist.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
readahead.c mm: silently skip readahead for DAX inodes 2016-08-26 17:39:35 -07:00
rmap.c rmap: fix compound check logic in page_remove_file_rmap 2016-08-10 16:40:56 -07:00
shmem.c huge tmpfs: fix Committed_AS leak 2016-09-24 11:20:01 -07:00
slab_common.c mm: charge/uncharge kmemcg from generic page allocator paths 2016-07-26 16:19:19 -07:00
slab.c Implements HARDENED_USERCOPY verification of copy_to_user/copy_from_user 2016-08-08 14:48:14 -07:00
slab.h mm, kasan: switch SLUB to stackdepot, enable memory quarantine for SLUB 2016-07-28 16:07:41 -07:00
slob.c mm: slab: free kmem_cache_node after destroy sysfs file 2016-02-18 16:23:24 -08:00
slub.c mm/slub.c: run free_partial() outside of the kmem_cache_node->list_lock 2016-08-10 16:40:56 -07:00
sparse-vmemmap.c treewide: replace obsolete _refok by __ref 2016-08-02 17:31:41 -04:00
sparse.c treewide: replace obsolete _refok by __ref 2016-08-02 17:31:41 -04:00
swap_cgroup.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
swap_state.c mm: move most file-based accounting to the node 2016-07-28 16:07:41 -07:00
swap.c mm, pagevec: release/reacquire lru_lock on pgdat change 2016-07-28 16:07:41 -07:00
swapfile.c mm: fix the page_swap_info() BUG_ON check 2016-09-19 15:36:17 -07:00
truncate.c truncate: handle file thp 2016-07-26 16:19:19 -07:00
usercopy.c mm: usercopy: Check for module addresses 2016-09-20 16:07:39 -07:00
userfaultfd.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
util.c mm: move most file-based accounting to the node 2016-07-28 16:07:41 -07:00
vmacache.c
vmalloc.c mm: charge/uncharge kmemcg from generic page allocator paths 2016-07-26 16:19:19 -07:00
vmpressure.c mm/vmpressure.c: fix subtree pressure detection 2016-02-03 08:28:43 -08:00
vmscan.c mm: delete unnecessary and unsafe init_tlb_ubc() 2016-09-24 11:20:01 -07:00
vmstat.c mm: remove reclaim and compaction retry approximations 2016-07-28 16:07:41 -07:00
workingset.c mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page() 2016-09-30 15:26:52 -07:00
z3fold.c mm/z3fold.c: avoid modifying HEADLESS page and minor cleanup 2016-06-03 16:02:55 -07:00
zbud.c mm/zbud.c: use list_last_entry() instead of list_tail_entry() 2016-01-15 11:40:52 -08:00
zpool.c
zsmalloc.c zsmalloc: Delete an unnecessary check before the function call "iput" 2016-07-28 16:07:41 -07:00
zswap.c mm/zswap: use workqueue to destroy pool 2016-05-20 17:58:30 -07:00